The long-term goal of the proposed research is the increased understanding of the neural control of eye movement. The major aim during the requested grant period will be the clarification of the role of the cerebral cortex in oculomotor control, with particular emphasis on the contribution of posterior parietal association cortex. This region is of special interest because several lines of evidence indicate that the inferior parietal lobule (area 7 of Brodmann) may be involved in the initiation and control of eye movements concerned with the maintenance of gaze upon a visual target. Certain classes of neurons in area 7 become active before and during visually-evoked saccades and visual tracking, while other classes are active during the fixation of interesting targets in certain areas of visual space. The proposed research will determine whether axons from these saccade, tracking, and fixation cells of area 7 project directly to other areas of the nervous system which are known to be concerned with eye movement control, such as the brainstem oculomotor system or the frontal eye fields. The method of single-unit analysis in monkeys which have been trained to perform oculomotor tasks will be combined with the method of antidromic activation of the axons of area 7 cells produced by chronic stimulating electrodes placed in likely anatomical projection target regions. A second goal for the proposed grant period is to determine quantitatively the oculomotor deficits which follow surgical ablation or area 7 in combination with the frontal eye fields in behaviorally-trained monkeys. Information from this study will contribute to our understanding of the basic mechanisms of neural control of behavior, which will in turn aid us in our understanding of congenital and acquired disorders of nervous system function. In addition, these studies will eventually provide improved tools for diagnosis and evaluation of nervous system function in patients following stroke or trauma, and also in the many progressive conditions which are known to affect oculomotor control, such as tumors, myesthenia gravis, Alzheimer's disease, schizophrenia, and multiple sclerosis.